Used Mustangs values sink like a stone. I bought my car for almost 1/2 of sticker last year with 18k miles on it. It is a 2011 Loaded GT/CS convertible bought in sept 2013.
Sticker was 45K bought for 24 K. Rumor had it that these were going over sticker at the time do to the new motor and such so maybe the seller took an even larger bath on it.
See eBay completed sold auctions to get the best idea of what the street value is, And dont forget if he trades it to the dealer on a new car the trade value does not get taxed on the new car.
1987 5.0 LX ( sold in 92)
2011 GT/CS Convertible .Electronics package,
Security package,HID headlights,comfort package